the is operator now works with type classes and type variables

bugfixes:
the DLL tests were failing on Mac OS X, due to an incorrect DynlibFormat

tests/compile/tisop.nim

@@ -0,0 +1,42 @@
+import typetraits
+
+type
+  TRecord = (tuple) or (object)
+  
+  TFoo[T, U] = object
+    x: int
+
+    when T is string:
+      y: float
+    else:
+      y: string
+
+    when U is TRecord:
+      z: float
+
+  E = enum A, B, C
+
+macro m(t: typedesc): typedesc =
+  if t is enum:
+    result = string
+  else:
+    result = int
+
+var f: TFoo[int, int]
+static: assert(f.y.type.name == "string")
+
+when compiles(f.z):
+  {.error: "Foo should not have a `z` field".}
+
+proc p(a, b) =
+  when a.type is int:
+    static: assert false
+
+  var f: TFoo[m(a.type), b.type]
+  static:
+    assert f.x.type.name == "int"
+    assert f.y.type.name == "float"
+    assert f.z.type.name == "float"
+
+p(A, f)
+

tests/compile/ttypeclasses.nim

@@ -2,8 +2,8 @@ type
   TFoo[T] = object
     val: T
 
-  T1 = distinct expr
-  T2 = distinct expr
+  T1 = expr
+  T2 = expr
 
 proc takesExpr(x, y) =
   echo x, y

tests/reject/tcaseexpr1.nim

@@ -1,11 +1,11 @@
 discard """
   file: "tcaseexpr1.nim"
 
-  line: 23
-  errormsg: "not all cases are covered"
-
   line: 29
   errormsg: "type mismatch: got (string) but expected 'int'"
+
+  line: 23
+  errormsg: "not all cases are covered"
 """
 
 type

tests/reject/tenummix.nim

@@ -1,6 +1,6 @@
 discard """
   file: "system.nim"
-  line: 643
+  line: 649
   errormsg: "type mismatch"
 """